Recently, the technology to prevent stains on the surface of a variety of materials by providing the surface with hydrophilic property using a photocatalytic activity has drawn an attention (see, Japanese Patent Application Laid-Open No. 9-57912), and coating agents for providing hydrophilic films on the surface of materials have been commercially available. However, the films made from the coating agents have not shown a hydrophilicity enough to sufficiently prevent stains under the light irradiation. Especially, when utilized indoors, the films made from the coating agents have sometimes had an insufficient hydrophilicity under light irradiation by illuminator.